OK. Half of you are thinking you cannot choose just one, and the other half cannot choose at all because I left off your medium, that devious, elusive, fantastic number 8. Then, a third half (look, I'm a writer, not a mathematician) is thinking, "Illustration? Do you mean like drawing, calligraphy, cartooning, or napkin sketching?"
Since a complete list is a futile effort, how about telling me. Your art? Name it.